Additive and Multiplicative Uncertainty Revisited: What Explains the Contrasting Biases?

above the certainty level while for additive uncertainty the price should be lower than the certainty level. This note gives an intuitive explanation for the result after first presenting a parsimonious review of the two models. We also discuss which, if either, of the two models is more realistic. Received December 14, 2001; revised version received July 16, 2002 Published online: April 30, 2003 We thank referees for helpful comments. Ciaran Driver would like to acknowledge the research facilities from ANU, Canberra for their help in writing this paper.     

Model Uncertainty, Optimal Monetary Policy and the Preferences of the Fed

Monetary policy in the US is characterized by a substantial degree of inertia. While in principle this may well be the outcome of an optimizing central bank behaviour, the ability of any derived policy rule to match the data relies on so large weights for interest rate smoothing into policy makers' preferences as to be theoretically flawed. In this paper we investigate whether such a puzzle can be interpreted as resulting from the concern of monetary authorities for potential misspecifications of the macroeconomic dynamics. Accordingly, we propose a novel thick modelling approach that incorporates model uncertainty into the identification of central bank's preferences. The thick robust policy rule shows the kind of smoothness observed in the data without resorting to implausible values for the preference parameters.     

Certainty Independence and the Separation of Utility and Beliefs

Economists often operate under an implicit assumption that the tastes of a decision maker are quite stable, while his beliefs change with the availability of new information. We show that for a general class of preferences, a separation of a key component of tastes, the utility function, from the other components of the representation is possible only if the decision maker's preferences satisfy a mild but not completely innocuous condition, called ‘certainty independence’. We also outline the axiomatic characterization of the preferences that obtain such separation, which are a subset of the biseparable preferences.     

iTV: A major opportunity for financial services,or not?

Interactive television has arrived, thanks to substantial technology investments that have been made by Sky and others. It is growing in importance as innovative interactive applications are developed for broadcast programmes (eg the BBCi service and Big Brother), and for advertising — and will develop further when broadband deployment gets to critical mass. Readers should not expect a television-variant of the world wide web, however. This was tried during 2000–2002 in the form of web look-alike, interactive ‘walled garden’ sites, and failed to attract critical mass footfall. The model has evolved and now revolves around interactive content synchronised with broadcast, which offers financial services companies an interesting new way to increase awareness and to differentiate the service presentation. Furthermore, over the next ten years, broadband is expected to usher in a new era of personalised television — in which specialised broadcasts (such as personal pensions advice programmes) can be made available on demand. The observations in this paper are mainly drawn from the UK, where digital television penetration is high; the lessons can be applied more broadly, however, and are relevant to any organisation thinking of promoting its service through entertainment channels.